I wouldn’t doubt this. I know when I fall into a deep sleep my body becomes a heat pump which is great during the winter and not so great during the summer. I’m sure it burns more cals when it’s putting off the heat. Then there’s the importance of just getting the proper rest which I know is different for everyone.
Some lucky people can get by with as little 5 hours of sleep a night. Most need 7 or more.
What’s sleep?